DNS issues on ISPConfig 3 on VPS

just built ISPConfig 3 on Centos 5.6 - i386 on a VPS server. All running fine except seeing problems with DNS. Its a bit complicated to explain but so far it goes like this...

the hostname is vps01.mbitservices.com.au the public ip address of my vps is 103.1.185.18

I am hosting x3 sites on it , I own the domain names registered at Crazy Domains:

mbitservices.com.au
markberrymusic.com
openheartliving.com

I have added DNS zones into ISPConfig 3 for all the above and I am setting
ns1.mbitservices.com.au with an A record : 103.1.185.18 on each site within ISPConfig 3. As the first name server and Crazy Domains relevant name server as the second NS.

I have added the glue record ns1.mbitservices.com.au as ip 103.1.185.18 into Crazy domains for the site mbitservices.com.au

mbitservices.com.au is working fine on the internet
the other two are not

even if I ping from a shell into my VPS I cannot ping those sites.
and nslookup suggests the DNS is actually using the VPS hosts Name servers

thanks for the suggestion, it nearly worked, I am now able to access the sites using

markberrymusic.com
openheartliving.com

but if I put www. in front of them it fails.

lookups for both www. and without supposedly resolve to 103.1.185.18 , and I am pretty sure I have setup the ISPConfig 3 correctly according to the manual...

I have the auto-subdomain set to 'www.' in the sites section
I have the A records for both domains set for 'www' as well as MX records and everything that would normally be created using the domain zone wizard setup in ISPConfig 3 is set.

Thanks Falko it put me onto a solution though I am not sure it is supposed to be done this way at least it works and everything is up and running.

I basically have had to create a separate name server for each domain zone and then set that as the name server with a glue record for each domain back at Crazy domains.

e.g. I have ns1.markberrymusic.com added into that domain zone on ISPConfig as an A record and as the primary name server, and then set it again as a glue record at crazy domains, and I have done this the same for each site I have on ISPconfig.

I dont think this is how it is supposed to be set up but its working, I am still convinced something is wrong in the bind chroot DNS setup somewhere on my server but hell, if it works I dont much care

thanks for the input. hopefully that will be it now and I can finally get some sleep.

its finally fixed. I dont know if it is really the solution but the solution came about after the following.

putting two NS Servers records in the ISPConfig 3 DNS zones instead of just one ns server seemed to solve the problem.

i.e. I now have ns1.mbitservices.com.au and ns2.mbitservices.com.au both set as
my ISCconfig public ip address. And I add these as both ns servers for each site. entered both at the registrar for the site,
and in ISPConfig and voila, all new sites work.